The impact of climatic change on nigerian landcover during the el-nino southern oscillations (ENSO), event of 1997 to 1998
Research Journal of Applied Sciences
Department of Environmental Sciences, Federal University, P.M.B. 7156, Dutse Jigawa State, Nigeria; Department of Geography, Usmanu Danfodiyo University, P.M.B. 2346, Sokoto, Nigeria
Seventytwo dekadal NDVI dataset derived from Advanced Very High Resolution Radiometer-Normalised Difference Vegetation Index (AVHRR-NDVI) on board the National Oceanic Atmospheric Administration-National Aeronautics Space Administration (NOAA-NASA) meteorological satellites were recomposed into a 24 time-series monthly Maximum Value Composite (MVC) images covering the El-Nino Southern Oscillations (ENSO) event of 1997 to 1998 and analysed within a Geographical Information System (GIS) environment using Principal Component Analysis (PCA) with the standardised principal components and supplemented with coefficient of variation derived images. The purpose is to assess the impact of such event on landcover across Nigeria and in particular, vegetation patterns across the country. Results from this analysis produced 24 standardised principal component imageries with another corresponding 24 individual loading scores presented in graphs. Others include inter-seasonal coefficient of variation change images for 1997 and 1998 as well as an annual mean NDVI image of the total 24 time-series dataset; temporal profiles of sites observed with distinct changes and a coefficient of variation graph through the monthly time-series were presented. The resultant component one image shows an overall 96.5% of the variation in the total time-series dataset while the succeeding imageries illustrated change elements in the order of the component loadings (which are weighted). In comparison with the mean imagery of the total 24 time-series dataset, the first component image showed a considerable similarity indicating a typical characteristic of landcover (particularly vegetation NDVI) pattern over the whole country during the 1997 to 1998 ENSO event with positive and negative anomalies in certain locations across some states but more distinct in locations around the Kainji and Lake Chad basins, Niger delta area, Bayelsa, Lagos, Taraba, Plateau, Jigawa, Katsina, Sokoto, Zamfara Adamawa, Yobe and Bomo states. Thus, results from this study highlighted specific locations across the country with anomalies of climatic impact as a result of the 1997 to 1998 ENSO event. © Medwell Journals, 2013.